本論文提出了一種新型變磁通對沖式永磁同步電機（variable-flux spoke-type permanent magnet synchronous motor, VFS-PMSM），其調節氣隙磁通方法與傳統不同，乃是透過磁石中的磁極方向“旋轉”來達成。本論文將所提出的VFS-PMSM 與其他兩種變磁通馬達比較，亦即結合高矯頑力和低矯頑力磁石之串聯和並聯型變磁通馬達，發現所提出馬達的等效磁路在磁通增強模式時與串聯型相同，在磁通弱化模式時與並聯型相同。因此VFS-PMSM可以同時具備兩者的優點，且無論何時低矯頑力磁鐵的操作點皆保持在安全範圍內。除了等向性低矯頑磁力磁石之外，本論文亦研究異向性低矯頑力磁石在VFS-PMSM中的應用，其挑戰在於旋轉異向性低矯頑力磁石的磁極方向的可行性，以及異向性磁石的不同磁化強度對電機性能的影響。本論文通過實驗研究了旋轉異向性低矯頑力磁石磁化方向的可行性，證實磁化方向可在較低外部磁場以及充磁電流的情況下成功將磁極旋轉 90 度。本文並提出了三種VFS-PMSM 拓撲，並比較此三種拓撲、串聯型、並聯型和各種轉子配置的關鍵性能指標，以確定提高性能的關鍵。透過有限元素分析模擬，與串聯型相比，在相同最大扭矩的情況下，磁通調節能力可提高26.84%。最後進行原型機實測，驗證設計之可行性。

This dissertation proposes a novel variable-flux spoke-type permanent magnet synchronous motor (VFS-PMSM), whose air gap flux density can be adjusted by “swiveling” magnetic pole directions in permanent magnet (PM). This is distinctive from conventional methods that require a large magnetizing field to magnetize and demagnetize rotor PM along the same axis for variable flux motors. This dissertation compares the proposed VFS-PMSM with two other typical types, i.e., series and parallel arrangements combining high- and low-coercivity PMs to achieve variable flux. It is found that the magnetic circuit of the proposed motor is identical to that of the series type at flux enhancing and to that of the parallel type at flux weakening. Therefore, the wide flux regulation range of the parallel type motors and the excellent on-load demagnetization-resisting capability of the series type motors can both be achieved in the proposed design. Another benefit is that the flux of the low-coercivity magnet constantly or aligns with that of the high-coercivity one whether the motor is flux enhanced or weakened. This allows the low-coercivity magnet to maintain its operating point within a safe range. This dissertation also investigates the application of anisotropic low-coercive force (LCF) magnets to VFS-PMSM. The challenge thus lies in the feasibility to swivel the magnetic pole direction of the anisotropic LCF magnet, and the impact of the different magnetization strengths of the anisotropic magnets on the motor performance. This dissertation studies the feasibility to swivel the magnetization direction of anisotropic LCF magnets through experiments. It is confirmed that the magnetization direction can be successfully swiveled by 90 degrees with a reduced external magnetizing field and current.
Then, three VFS-PMSM topologies, series type, parallel type and various rotor configurations are compared in terms of key performance indices to determine critical sizing factors for performance enhancement. Finite element analysis is used for simulations. In comparison with the series type, the flux adjustment ability can be enhanced by 26.84% for the same maximum torque. Finally, measurements are conducted on the prototype to verify the feasibility.

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